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Thousands of cars line up to enter the US at the San Ysidro Port of Entry January 27, 2006 in San Ysidro, Calif. - 


BOB MOON: A hearing is being held on Capitol Hill today to examine how proposed changes in immigration policy might affect small businesses. Several recent studies have addressed the opposite question: How do changes in business conditions affect the flow of illegal immigrants? From the Americas Desk at WLRN, Dan Grech has more.

DAN GRECH: Dawn McLaren at Arizona State University studied 16 years of Border Patrol data, and found a startling trend: A full year before an economic downturn, the number of migrants apprehended at the Mexican border began to drop.

DAWN MCLAREN: About a year ago, I looked at it, and I said, "Hmm, we've gotten to a turning point, because apprehensions are starting to slow down."

Apprehensions have now fallen 12 months in a row — a total drop of 27 percent.

MCLAREN: And sure enough, a year later, instead of 5.6 percent growth, we've got 1.3 percent growth in our economy.

Economist Pia Orrenius is with the Federal Reserve Bank of Dallas.

PIA ORRENIUS: It's very closely correlated with how sectors are doing that employ a lot of immigrants, like construction, like agriculture and like manufacturing.

With the housing bubble burst, economists expect the slowdown in illegal immigration to continue.

I'm Dan Grech for Marketplace.